In order to draw something accurately in the ancient Beaux Arts tradition, to get a likeness of it, you have to observe it very closely. Even the space around it is as important as the curves and outlines of the thing itself. Draughtsmen look at things in a very particular way, and the more they study the more they understand what the world looks like and how to represent it.

The brain plays tricks on the eye. For instance, the top of a matchbox is wider than it is deep. But look at a matchbox from the side, with the top receding sharply from you, and the opposite is true. If you rely on your memory alone you will find that you are drawing a matchbox all wrong. Noticing such oddities and training your hand to obey your eyes, even though your eyes seem to be lying, is a large part of why drawing is so fascinating.

There are other surprises. For instance, because you know that objects are completely separate from each other, you will tend to draw them that way. In fact, the tone of the shadowed side of a matchbox may be exactly the same as the wall behind it. To represent them accurately you may have to leave part of the outline indistinct. In real life, objects often appear to blur and melt into each other.

A glance at the work of great draughtsmen such as Rembrandt or Michelangelo reveals how closely they observed their motifs. Such diligence is less obvious in the simplified drawings of Japanese Zen masters, for example. But their art is not as dashed off as it looks. No one could possibly draw so beautifully without years of study and practice.

With this in mind, I have always been puzzled by 30,000 year old cave paintings. How on earth did such primitive societies produce those superb artists? The answer is: they had art schools.

I know ... but there is no other explaination.

—N.G.